The present invention relates, in general, to crane assemblies, and more particularly, relates to a vehicle mounted crane assembly of the type which can be used in small or medium sized construction projects.
Residential and light industrial building contractors are often met with the need for a lightweight, easily transportable crane. Such a crane is not normally required throughout the building project, but there are many lifting jobs, such as the lifting of heavy beams, structural components and equipment, which are facilitated by, or absolutely require, a crane.
Presently, contractors typically satisfy this need by renting relatively large crane assemblies which are permanently mounted on a truck and can be brought to the job site to perform the various lifting tasks. Since the rental of such equipment is expensive, the contractor must carefully plan the critical path of construction which will minimize the number of days during which the crane is at the building site. Even with the best of planning, there will often be situations in which the crane either must be at the site and not in use, or taken away from the site and then returned at a later date. Both approaches add undesirably to the cost of using such equipment and tend to make its use relatively inconvenient. Moreover, often borderline jobs are attempted with inadequate lifting equipment in order to try to avoid the necessity of using crane time or returning the crane to the site.
Generally speaking the cost of conventional truck mounted cranes is so substantial that small or medium size contractors do not own such equipment themselves. Additionally, such truck mounted cranes often are of a size which require special permits to transport the same over city streets in urban areas. Alternatively, such cranes often include lifting booms that are segmented and must be taken apart and then reassembled at the site in order to enable transport on city streets.
Another alternative is to employ an extremely large crane which can be brought to the building site in sections and assembled or erected on the site. Such cranes remain in place throughout the building process, and accordingly are expensive and not used for smaller jobs.